From Longman Dictionary of Contemporary Englishoctagonoc‧ta‧gon /ˈɒktəɡən $ ˈɑːktəɡɑːn/ noun [countable] CFa flat shape with eight sides and eight angles —octagonal /ɒkˈtæɡənəl $ ɑːk-/ adjective an octagonal tower
Examples from the Corpus
octagon• An ambulatory round the central octagon joins together the four chapels of the smaller ones.• The big trap in dealing with the Duveen Galleries is the centre octagon.• This main octagon is the central chamber or nave.• The result should be a perfect octagon.• Loops of wire pressed octagons into her face, just below the hairline, imprinting a headdress of chains.• At four corners are smaller octagons, replicas in design of the large one and all very tall.• Here, the old central tower over the crossing was replaced by the unique octagon and lantern.Origin octagon (1500-1600) Latin octagonum, from Greek, from okta- “eight” + -gonon “-gon” 